In the prior art, so-called “PCV valves” have been proposed and used. “PCV” means “positive crankcase ventilation” and is a ventilation valve, especially a volume flow control valve or flow rate control valve, which is supposed to ensure, for example, that the engine, especially of an automotive, is well ventilated by allowing part of the intake air to escape through the crankcase via this ventilation at idling speed, and when the load is low. Contamination of the engine oil by condensates is to be reduced thereby.
Usually, a piston in this valve regulates an opening cross-section that controls the air flow to the intake manifold or intake tract by means of a spring so that only a defined small amount of gas is allowed to pass, and thus the pressure difference is controlled.
DE 20 2010 001 191 01 U1 describes a valve for controlling a gas flow, a liquid separator, a ventilation system, and an internal combustion engine having such a valve. This utility model relates to a valve for controlling a gas flow from a discharge side to a suction side of the valve, comprising a valve closure, especially a valve disk, a valve opening closable by means of a valve closure, and a valve bearing in which the valve closure is supported by a spring, characterized in that said valve closure has one or more gas passing openings from the discharge side to the suction side of the valve.
DE 10 2008 005 409 B4 relates to a valve for ventilating the crankcase of an internal combustion engine. The patent relates to a valve for ventilating the crankcase of an internal combustion engine, wherein the valve comprises a fresh-air side for connection with an intake section, an engine side for connection with the crankcase and a valve insert movable as a whole for changing the flow resistance through the valve, wherein said valve insert is held inside said valve without preload, wherein a negative pressure on the fresh-air side relative to the engine side causes free displacement of the valve insert to a ventilation limit-stop position, and excess pressure on the fresh-air side relative to the engine side causes free displacement of the valve insert to another limit-stop position, wherein the valve insert is designed to open a ventilation cross-section in the ventilation limit-stop position, and wherein said valve insert has a covering element for covering at least one passage opening in said valve, wherein said covering element opens said at least one passage opening in a limit-stop position, and in the other limit-stop position, which is an aeration limit-stop position, opens an aeration cross-section that is different from the ventilation cross-section, and at least one passage opening is provided between the fresh-air side and the engine side, which is open independently of the position of the valve insert, in order to supply fresh air through the passage opening to the crankcase in the aeration limit-stop position, and to discharge blow-by gas through the passage opening from the crankcase in the ventilation limit-stop position.
DE 40 22 129 C2 relates to a pressure-control valve to be incorporated in a ventilation duct on an internal combustion engine. The pressure-control valve is characterized in that an intermediate valve is arranged between the valve plate of the diaphragm and the first valve seat at the bottom of the housing, which intermediate valve has a second valve seat facing towards the diaphragm and cooperates with the valve plate of the diaphragm, and comprises a valve plate facing towards the valve seat of the bottom of the housing and cooperates with it, wherein said intermediate valve is provided on the diaphragm in such a way that an axial relative movement between the diaphragm and the intermediate valve is possible.
U.S. Pat. No. 3,308,798 A describes a metering valve for a crankcase ventilation system.
U.S. Pat. No. 3,111,138 A describes a crankcase ventilation regulator.
In a similar way, the gas flow and the pressure drop are controlled by pressure-control valves with an elastomer diaphragm and a compression spring, or with the above mentioned PCV valves with a piston and compression spring in the prior art (DE 10 2009 012 872 A1; U.S. Pat. No. 3,645,242 A).
In particular, compression springs have also been used for regulating a diaphragm or the piston with a correspondingly large mounting space required. The oil separation was arranged separately. However, these require more mounting space, wherein the high flow rate required by the valve was not utilized for droplet separation from the blow-by gas.